Set of headphones



FIG. 1 is a perspective view of a set of headphones as seen from the front, top and left side;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a side view thereof;

FIG. 5 is an opposite side view thereof;

FIG. 6 is a bottom view thereof; and,

FIG. 7 is a top view thereof.

The dotted line portions of the drawings represent environmental structure only and do not form part of the claimed design. 

The ornamental design for a set of headphones, substantially as shown and described. 